The Tweed is a river famed first and foremost for its prolific run of salmon – an annual event that attracts anglers from all corners of the globe. Yet the silvery migrant is not the only gamefish lurking in its waters, and for some anglers the ultimate prize is rather more elusive. Indeed, as I was to discover, for men such as ‘Big’ Ron McCombe the elegance of the grayling makes it a far nobler quarry than the salmon. And as I headed with Big Ron down to the river’s Tweedswood beat, beneath the soaring sandstone arches of the Victorian viaduct, my guide for the day began to explain a few things about a fish which I’d never encountered, let alone caught. Perhaps the most remarkable of its attributes was that grayling smell not slimy and piscine, but instead give off the distinctive aroma of thyme – the herb that explains Thymallus thymallus, the fish’s Latin name.

Although not native to Scotland, grayling were introduced from the Derbyshire Wye in the mid-19th century, and now thrive in rivers from the Tweed right up to the Tummel. According to Ron, it is the former river that holds some of Scotland’s largest specimens, with fish of well over three pounds regularly caught. Yet, despite these attributes, and the fact that it is both beautiful to behold and excellent eating, the grayling has long been treated as vermin by salmon anglers, who have tended to knock it on the head and leave it as crow-fodder. However, Big Ron explained, the fish has experienced something of a renaissance in recent years and is increasingly seen as a fly-fisher’s quarry in its own right. This status is enhanced by the fact that unlike its more illustrious cousins, salmon and trout, the grayling can be fished for all year round, which explained what I was doing on the Tweed in mid-January, when other salmonids were off limits. And it was clear that Ron was far from the only grayling afficionado in the area – as we were getting ready Peter, a fellow enthusiast who was walking the riverbank, came over to wax lyrical about the charms of ‘The Lady of the Stream’.

Apparently some 70 people had turned up to Earlston Angling Club’s competition a fortnight before, landing over 130 of the fish. The grayling clearly holds considerable appeal, I reflected, especially if it was capable of luring so many fisherfolk out in winter’s icy depths. But, with frost on the ground and frigid fog cloaking the river, I was beginning to doubt the sanity of either Big Ron, Peter, or the other 68 competitors – hibernation was surely a more sensible option than standing waist-deep in water which felt like it flowed from the wastes of the Arctic rather than from amidst the gentle contours of the Lowther Hills. If I was to catch anything, I began to suspect, it would probably be not the rare beauty of the grayling, but merely the more familiar unsightliness of the common cold. However, Big Ron proved more optimistic. Although, he confessed, the fish were easier to locate in lower water conditions, the river levels were by no means impossibly high. And, clad in waders, jackets, hats, gloves, scarves, vests, long johns and multiple jumpers – all essential items for mid-January fishing – we waddled, like neoprene penguins, up to the head of the Tweedswood Pool.

Although I’d fished regularly since a nipper, it soon became apparent that I’d have to unlearn over two decades of trial and error and abandon traditional methods in favour of a technique perfected by the Czechs. This, Ron demonstrated, involved casting a heavy fly, on a short line, 45 degrees upstream and letting it bounce down along the bottom, where the grayling would be busy hoovering food from the river floor. While the casting wasn’t so testing, the trick, Ron explained, was to know when a bump on the line was a fish and when it was merely part of the river bed. Therein, he said, lies the art. Twitch, bump, strike – nothing; twitch, bump, strike – twig; twitch, bump, strike – leaf; twitch, bump, strike – thin air!

Every few casts contained a moment when I felt my fly was being drawn softly into a waiting grayling’s downwardpointing mouth, but either I was too slow to raise my rod tip or the fly emerged with pieces of plant matter, not a hard-fighting fish, attached. After a couple of fishless, but by no means joyless, hours of twitching and bumping I felt it was time to defrost. Big Ron, thankfully, agreed – apparently three or four hours is as long as most people spend in pursuit of the grayling at this time of year, especially if the fish were proving elusive.

As I headed back to Edinburgh and the feeling slowly crept back into my frozen feet, so too did my resolve to return. I had failed to encounter a grayling on this occasion, but, I hoped, my thyme would come one winter soon.

Field Facts This trip was organised by Tweed Guide – a company that arranges guided fly fishing days for salmon, trout, sea trout and grayling on the River Tweed and its tributaries. Tel: 07962 401 770, www.tweedguide.com